package corejava.ThreadPoolTest;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Scanner;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutionException;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Future;

/**
 * This task counts the files in a directory and its subdirectories that contain a given keyword.
 */
public class MatchCounter implements Callable<Integer> {
    /**
     * Constructs a MatchCounter.
     * @param directory the directory in which to start the search
     * @param keyword the keyword to look for
     * @param pool the thread pool for submitting subtasks
     */
    public MatchCounter(File directory, String keyword, ExecutorService pool) {
        this.directory = directory;
        this.keyword = keyword;
        this.pool = pool;
    }

    public Integer call() {
        count = 0;
        try {
            File[] files = directory.listFiles();
            ArrayList<Future<Integer>> results = new ArrayList<Future<Integer>>();

            for (File file : files)
                if (file.isDirectory()) {
                    MatchCounter counter = new MatchCounter(file, keyword, pool);
                    Future<Integer> result = pool.submit(counter);
                    results.add(result);
                } else {
                    if (search(file))
                        count++;
                }

            for (Future<Integer> result : results)
                try {
                    count += result.get();
                } catch (ExecutionException e) {
                    e.printStackTrace();
                }
        } catch (InterruptedException e) {
        }
        return count;
    }

    /**
     * Searches a file for a given keyword.
     * @param file the file to search
     * @return true if the keyword is contained in the file
     */
    public boolean search(File file) {
        try {
            Scanner in = new Scanner(new FileInputStream(file));
            boolean found = false;
            while (!found && in.hasNextLine()) {
                String line = in.nextLine();
                if (line.contains(keyword))
                    found = true;
            }
            in.close();
            return found;
        } catch (IOException e) {
            return false;
        }
    }

    private File            directory;
    private String          keyword;
    private ExecutorService pool;
    private int             count;
}